Active Control of Laminar Boundary Layer Disturbances

Abstract

Active suppression of the naturally occurring travelling wave disturbances that amplify in laminar boundary layers and cause the transition from laminar to turbulent flow is considered. Both open-loop and closed-loop schemes are discussed. Numerical predictions, based on linear stability theory, have been used to model the behaviour of the flow disturbances and the controlled waves. Predictions based on these models have shown that the instability waves that occur on a simple flat plate can be stabilized significantly by both types of control.Wind tunnel experiments have so far been used to validate some of the predictions in the open-loop case.